Tissues in Action

A tissue is a group of similar cells doing one job. Plants have meristematic and permanent tissues; animals have epithelial, connective, muscular and nervous tissue.

Key ideas

Meristematic tissue keeps dividing: apical (tips, length), lateral (sides, girth) and intercalary (base of leaves, grasses).
Simple permanent tissues: parenchyma (stores food), collenchyma (flexibility), sclerenchyma (hard, dead cells with lignin).
Xylem carries water and minerals up; phloem carries food both ways.
Epithelium covers and lines organs: squamous (blood vessels, skin), cuboidal (kidney tubules), columnar, ciliated (windpipe).
Muscles: striated (voluntary, on bones), smooth (involuntary, gut and blood vessels), cardiac (heart, never tires).
A neuron has a cell body, dendrites and a long axon; it carries messages as electrical signals.

Remember

Tendon	joins muscle to bone (strong, little stretch)
Ligament	joins bone to bone (elastic)
Blood	plasma + red cells (oxygen) + white cells (defence) + platelets (clotting)
Cork and epidermis	protective tissues; cork walls have suberin

Watch out

Mixing up tendons and ligaments.
Calling xylem vessels living cells (mature vessels are dead tubes).
Saying cardiac muscle is voluntary.

Worked example

Say whether each is a plant or an animal tissue, and name its kind: smooth muscle; nervous tissue; epidermis; cork.

Working: plant tissues are meristematic, simple permanent, complex permanent or protective; animal tissues are epithelial, connective, muscular or nervous

Answer: smooth muscle: animal, muscular; nervous tissue: animal, nervous; epidermis: plant, protective; cork: plant, protective